DESCRIPTION: The proposers will investigate the effects of EMFs as a possible co-promoter in the C3H/10T1/2 system using a subline of this system whose expression of the neoplastic phenotype is modulated by the presence of retinoic acid. In particular, they will compare the effects of cells exposed intermittently to EMF to cells exposed continuously. They will measure patterns of p53 and myc expression at the transcriptional level and measure upstream molecular sequelae. They will determine the requirements for transcription factors in the expression of myc and p53, using a combination of reporter genes and electrophoretic mobility shift assays. Their studies will compare effects of EMF to chemical tumor promoters.